#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <locale.h>
#include <limits.h>
#include <wchar.h>

#include <time.h>

#include "putty.h"
#include "charset.h"
#include "terminal.h"
#include "misc.h"

/*
 * Unix Unicode-handling routines.
 */

int is_dbcs_leadbyte(int codepage, char byte)
{
	return 0;						   /* we don't do DBCS */
}

int mb_to_wc(int codepage, int flags, char *mbstr, int mblen,
			 wchar_t *wcstr, int wclen)
{
	if (codepage == DEFAULT_CODEPAGE) {
		int n = 0;
		mbstate_t state;

		memset(&state, 0, sizeof state);
		setlocale(LC_CTYPE, "");

		while (mblen > 0) {
			size_t i = mbrtowc(wcstr+n, mbstr, (size_t)mblen, &state);
			if (i == (size_t)-1 || i == (size_t)-2)
				break;
			n++;
			mbstr += i;
			mblen -= i;
		}

		setlocale(LC_CTYPE, "C");

		return n;
	} else if (codepage == CS_NONE) {
		int n = 0;

		while (mblen > 0) {
			wcstr[n] = 0xD800 | (mbstr[0] & 0xFF);
			n++;
			mbstr++;
			mblen--;
		}

		return n;
	} else
		return charset_to_unicode(&mbstr, &mblen, wcstr, wclen, codepage,
								  NULL, NULL, 0);
}

int wc_to_mb(int codepage, int flags, wchar_t *wcstr, int wclen,
			 char *mbstr, int mblen, char *defchr, int *defused,
			 struct unicode_data *ucsdata)
{
	/* FIXME: we should remove the defused param completely... */
	if (defused)
		*defused = 0;

	if (codepage == DEFAULT_CODEPAGE) {
		char output[MB_LEN_MAX];
		mbstate_t state;
		int n = 0;

		memset(&state, 0, sizeof state);
		setlocale(LC_CTYPE, "");

		while (wclen > 0) {
			int i = wcrtomb(output, wcstr[0], &state);
			if (i == (size_t)-1 || i > n - mblen)
				break;
			memcpy(mbstr+n, output, i);
			n += i;
			wcstr++;
			wclen--;
		}

		setlocale(LC_CTYPE, "C");

		return n;
	} else if (codepage == CS_NONE) {
		int n = 0;
		while (wclen > 0 && n < mblen) {
			if (*wcstr >= 0xD800 && *wcstr < 0xD900)
				mbstr[n++] = (*wcstr & 0xFF);
			else if (defchr)
				mbstr[n++] = *defchr;
			wcstr++;
			wclen--;
		}
		return n;
	} else {
		return charset_from_unicode(&wcstr, &wclen, mbstr, mblen, codepage,
									NULL, defchr?defchr:NULL, defchr?1:0);
	}
}

/*
 * Return value is TRUE if pterm is to run in direct-to-font mode.
 */
int init_ucs(struct unicode_data *ucsdata, char *linecharset,
			 int utf8_override, int font_charset, int vtmode)
{
	int i, ret = 0;

	/*
	 * In the platform-independent parts of the code, font_codepage
	 * is used only for system DBCS support - which we don't
	 * support at all. So we set this to something which will never
	 * be used.
	 */
	ucsdata->font_codepage = -1;

	/*
	 * If utf8_override is set and the POSIX locale settings
	 * dictate a UTF-8 character set, then just go straight for
	 * UTF-8.
	 */
	ucsdata->line_codepage = CS_NONE;
	if (utf8_override) {
		const char *s;
		if (((s = getenv("LC_ALL"))   && *s) ||
			((s = getenv("LC_CTYPE")) && *s) ||
			((s = getenv("LANG"))	  && *s)) {
			if (strstr(s, "UTF-8"))
				ucsdata->line_codepage = CS_UTF8;
		}
	}

	/*
	 * Failing that, line_codepage should be decoded from the
	 * specification in cfg.
	 */
	if (ucsdata->line_codepage == CS_NONE)
		ucsdata->line_codepage = decode_codepage(linecharset);

	/*
	 * If line_codepage is _still_ CS_NONE, we assume we're using
	 * the font's own encoding. This has been passed in to us, so
	 * we use that. If it's still CS_NONE after _that_ - i.e. the
	 * font we were given had an incomprehensible charset - then we
	 * fall back to using the D800 page.
	 */
	if (ucsdata->line_codepage == CS_NONE)
		ucsdata->line_codepage = font_charset;

	if (ucsdata->line_codepage == CS_NONE)
		ret = 1;

	/*
	 * Set up unitab_line, by translating each individual character
	 * in the line codepage into Unicode.
	 */
	for (i = 0; i < 256; i++) {
		char c[1], *p;
		wchar_t wc[1];
		int len;
		c[0] = i;
		p = c;
		len = 1;
		if (ucsdata->line_codepage == CS_NONE)
			ucsdata->unitab_line[i] = 0xD800 | i;
		else if (1 == charset_to_unicode(&p, &len, wc, 1,
										 ucsdata->line_codepage,
										 NULL, L"", 0))
			ucsdata->unitab_line[i] = wc[0];
		else
			ucsdata->unitab_line[i] = 0xFFFD;
	}

	/*
	 * Set up unitab_xterm. This is the same as unitab_line except
	 * in the line-drawing regions, where it follows the Unicode
	 * encoding.
	 * 
	 * (Note that the strange X encoding of line-drawing characters
	 * in the bottom 32 glyphs of ISO8859-1 fonts is taken care of
	 * by the font encoding, which will spot such a font and act as
	 * if it were in a variant encoding of ISO8859-1.)
	 */
	for (i = 0; i < 256; i++) {
		static const wchar_t unitab_xterm_std[32] = {
			0x2666, 0x2592, 0x2409, 0x240c, 0x240d, 0x240a, 0x00b0, 0x00b1,
			0x2424, 0x240b, 0x2518, 0x2510, 0x250c, 0x2514, 0x253c, 0x23ba,
			0x23bb, 0x2500, 0x23bc, 0x23bd, 0x251c, 0x2524, 0x2534, 0x252c,
			0x2502, 0x2264, 0x2265, 0x03c0, 0x2260, 0x00a3, 0x00b7, 0x0020
		};
		static const wchar_t unitab_xterm_poorman[32] =
			L"*#****o~**+++++-----++++|****L. ";

		const wchar_t *ptr;

		if (vtmode == VT_POORMAN)
			ptr = unitab_xterm_poorman;
		else
			ptr = unitab_xterm_std;

		if (i >= 0x5F && i < 0x7F)
			ucsdata->unitab_xterm[i] = ptr[i & 0x1F];
		else
			ucsdata->unitab_xterm[i] = ucsdata->unitab_line[i];
	}

	/*
	 * Set up unitab_scoacs. The SCO Alternate Character Set is
	 * simply CP437.
	 */
	for (i = 0; i < 256; i++) {
		char c[1], *p;
		wchar_t wc[1];
		int len;
		c[0] = i;
		p = c;
		len = 1;
		if (1 == charset_to_unicode(&p, &len, wc, 1, CS_CP437, NULL, L"", 0))
			ucsdata->unitab_scoacs[i] = wc[0];
		else
			ucsdata->unitab_scoacs[i] = 0xFFFD;
	}

	/*
	 * Find the control characters in the line codepage. For
	 * direct-to-font mode using the D800 hack, we assume 00-1F and
	 * 7F are controls, but allow 80-9F through. (It's as good a
	 * guess as anything; and my bet is that half the weird fonts
	 * used in this way will be IBM or MS code pages anyway.)
	 */
	for (i = 0; i < 256; i++) {
		int lineval = ucsdata->unitab_line[i];
		if (lineval < ' ' || (lineval >= 0x7F && lineval < 0xA0) ||
			(lineval >= 0xD800 && lineval < 0xD820) || (lineval == 0xD87F))
			ucsdata->unitab_ctrl[i] = i;
		else
			ucsdata->unitab_ctrl[i] = 0xFF;
	}

	return ret;
}

const char *cp_name(int codepage)
{
	if (codepage == CS_NONE)
		return "Use font encoding";
	return charset_to_localenc(codepage);
}

const char *cp_enumerate(int index)
{
	int charset;
	if (index == 0)
		return "Use font encoding";
	charset = charset_localenc_nth(index-1);
	if (charset == CS_NONE)
		return NULL;
	return charset_to_localenc(charset);
}

int decode_codepage(char *cp_name)
{
	if (!*cp_name)
		return CS_NONE;				   /* use font encoding */
	return charset_from_localenc(cp_name);
}

